Goodhue resident Colin O'Connor, 5, puts the first geocache container back in its hiding place during a geocache outing at Carpenter Nature Center in Hastings, Sunday, September 16, 2012. (Pioneer Press: Chris Polydoroff)

Goodhue resident Bob O'Connor compares the GPS unit information with a map of Carpenter Nature Center in a quest to find the next cache in Hastings, Sunday, September 16, 2012. In the background, with stick, is his five year-old son Colin. (Pioneer Press: Chris Polydoroff)

My 10-year-old son walked in front of me down a trail through the woods, head bowed, staring at a cellphone in his palm. Really, I wasn’t letting him text in nature. We were geocaching.

Ten years ago, you would have had to explain the concept to everyone but tech geeks and wilderness buffs. Today, geocaching has gone mainstream, attracting an estimated 5 million people worldwide, including many families who geocache with children.

“Both my grandchildren do it with me,” says Deborah Schneider of St. Paul, an avid geocacher and member of the Minnesota Geocaching Association. “We’ve climbed fire towers on vacation to get caches. We’ve gone to islands out on lakes to get caches. We’ve climbed cliffs to get caches. How much fun is that?”

A lot of fun, which explains why geocaching continues to grow rapidly. Geocaching is a high-tech treasure hunt that involves using latitude and longitude coordinates to look for a container, often a Tupperware-type box with a few trinkets inside. Anyone can hide a cache and register its coordinates on the website geocaching.com. Anyone can look up the coordinates and search for the cache using a handheld GPS unit or a smartphone.

“I think it really taps into something that’s hardwired into not just kids’ DNA but also parents’ DNA, this need for exploration and desire to be a bit of an adventurer,” said Eric Schudiske, spokesman for the Seattle-based company Groundspeak.

While there are other geocaching sites, Groundspeak’s geocaching.com is the oldest and largest. It launched in 2000 and within a decade had registered 1 million caches. It is on track to hit 2 million by early next year.

ACCESSIBLE HOBBY

I decided to take my children on a search for one of the more than 20,000 caches hidden in Minnesota. Thanks to several geocaching apps, the hobby is now accessible to first-timers like me who are reluctant to buy a GPS unit just to try the game.

“I think the smartphone lowered the barrier of entry to geocaching,” Schudiske said. “No longer do you have to plug a GPS device into your computer and click and drag files and upload. The apps are designed so you can click a button. So if you’re in a parking lot and have 15 minutes of waiting with the kids, you can click and find a geocache nearby.”

I wanted a walk in the woods and an easy find for our first time — none of this climbing a tower stuff. After a bit of online research, I selected a cache at Fort Snelling State Park. In 2008, the Minnesota state parks were among the first to officially embrace geocaching by hiding a cache in every park with collector cards linked to the state’s 150th anniversary.

“We had someone complete all the caches in about a week. We were astonished,” said Kathy Dummer, who coordinates geocaching and other interpretive programs for Minnesota State Parks and Trails.

While participation was hard to track, Dummer estimates that 20,000 people found at least one of the caches before the challenge closed. A second geocaching challenge ran from 2009 to 2011. A third challenge called Geocaching Avian Adventure started in June 2012 and runs through June 2014.

New caches at every park are stocked with collectible cards depicting a different bird native to the state. Twenty-five parks also offer free loaner GPS units and instruction.

As we drove to Fort Snelling, I explained latitude and longitude to my children. The 6-year-old was delighted with the idea that the world is crisscrossed by imaginary lines.

My 10-year-old son thought it was cool that we live near the 45th parallel, half-way between the equator and the north pole. A boulder with a plaque sits on that parallel a block north of the intersection of Cleveland Avenue and Roselawn in Roseville. And yes, someone has created a cache at the site; it’s called Halfway There.

When we arrived at Fort Snelling, I parked near the swimming beach. I had downloaded the free app c:geo, which displayed our distance from the cache as about 800 meters. A compass with an arrow points toward the cache. You also can opt to navigate with a map or turn-by-turn instructions.

We picked a trail that headed in the direction we wanted to go, northeasterly, along a back channel of the Minnesota River. Despite enthusiasm for geocaching, park officials have been dismayed by people who bushwhack through fragile native plants to get to a cache. All caches in state park caches are accessible by trails, and you should stay on them.

We passed under the massive concrete arches of the Mendota Bridge while trucks rumbled overhead, drowning out the buzz of insects. At a fork in the path, we debated which way to go and opted for a trail that wandered through a shady grove littered with downed trees and rotting logs. Historic Fort Snelling was directly above us behind trees on the bluff top.

“We finally found the visitor center!” my son shouted, as the path opened into another parking lot and we beheld the building at the far end, as if we had stumbled on Shangri-La.

“Well, now we know where the bathroom is!” said my daughter.

“Oh my gosh, it’s pointing toward this thing,” my son said excitedly, holding the phone in his upturned palm as he circled an information kiosk. It took less than a minute to spot a wood box mounted on a side of the kiosk. New coordinates were printed on a laminated card on the underside of the lid.

HIDE AND SEEK

And here is where I hit a roadblock. The Avian Adventure caches are multi-stage caches, which means that at each stop, you find a new set of coordinates, leading to the next and so on before you reach the final hiding place.

The app had automatically loaded the first coordinates, but I could not figure out how to enter a second set of numbers. Yes, it would be a good idea to make sure I knew how to use my equipment before I left home, and yes, it would have been smart to visit when the visitor center was open, so I could have gotten help. But as someone once said, you learn more from your failures than your successes.

After five minutes watching me fiddle with my phone, my children became bored. After 10 minutes, they became irritated. After 30 minutes, they became hostile.

“You promised we could leave if you couldn’t figure it out in 15 minutes,” the 10-year-old yelled. “You always break your promises!”

As much as I hate to quit, it was time to bail. Luckily, one of the benefits of an app versus a GPS unit is the ability to look up caches on the go. I searched and found a nearby cache marked “River Cache: Historic Floods,” maintained by park rangers with the Mississippi National River and Recreation Area.

I handed the phone to my son, who recovered his good manners once he had something to do. We set down a paved trail lined with cottonwood trees.

Geocaching rules prohibit people from burying caches, but they can be stashed in logs or tree cavities, covered with a few leaves or pieces of bark, tucked behind boulders or under bridges or hidden just about anywhere. When our app said we were within 10 meters of the cache, we started looking around.

“Oh, Mom, come look,” said my daughter. I hurried to her side, only to find her crouched over an impressive, pale mushroom the size of my hand. “A fungus,” she declared.

Meanwhile, my son had spotted a flash of red, the lid of a Tupperware container.

“I found it!” he shouted.

The kids were giddy as they knelt in the leaves to open the box. Inside we found what’s called “swag,” trinkets you can take home, if you replace what you take with something of equal value. There was a bike reflector and a gold ribbon pin. My son selected a strand of plastic gold beads and my daughter took a Strawberry Shortcake ink stamp.

We left behind two cockle shells and signed the log book with our made-up-on-the-spot geocache nickname. A log is included in every cache. In this case, it was several strips of yellow paper held with a staple. We were the fifth to sign in September, after Bjardin, goldribbon, LaPenotiere and a smudged name I couldn’t read. We put the cache back exactly where we had found it, following another rule of the game.

On the geocaching.com website, I noted that since the cache was hidden three years ago, 150 people have found it and logged the find, but that doesn’t include people like us, who never get around to posting their results online.

Caches are often hidden in spots with historic significance, and this one was no exception. We walked out of the trees to a sandy beach on the Mississippi River, which the geocaching.com description identified as Steamboat Landing. A tall post was thrust into the top of the bank, painted with black lines marking the levels of historic floods. I reached high above my head, but the high water mark for 1965 was still several feet above my outstretched fingers.

Now that our eyes weren’t glued to the phone, we noticed our surroundings on a leisurely, mile-long walk back to the car. We passed a log and stone sculpture called Wokiksuye K’a Woyuonihan, honoring the 1,600 Dakota who were interned in the area after the U.S.-Dakota War of 1862. We chased big grasshoppers into the weeds and walked to the end of the fishing dock on Snelling Lake.

SOLVING PUZZLES

Park officials have embraced geocaching in part because it brings new visitors like us to places we would never otherwise visit. Certainly that’s also true of Tim McCollor of Minnetonka, who hit every single state park this summer with his sons Mark, 9 and Adam, 11.

“There are some parks that are really small and out of the way, and if you didn’t have a reason to go there, you wouldn’t,” said McCollor, who found the first cache on June 9 at Fort Snelling, the day the challenge was announced.

“Some days we would do five or six caches a day,” said McCollor, who works an every-other-week schedule as a hospital pharmacist and used his weeks off to camp around the state with his kids. “It was our mission.”

They were lucky to visit Jay Cooke State Park early in the summer, before it closed in the wake of storm damage. In mid-July they visited their last park and solved a puzzle that allowed them to find the final card at Itasca State Park.

McCollor’s advice for other parents? “Let the kids do as much as they can by themselves. They enjoy it more when they are the ones to find it.” The rule in their family is that whoever finds the cache lets the other brother take first pick of any swag.

The McCollors aren’t the only family deep into geocaching. Minnesota dad Joshua Johnson geocaches on his own and with his children and posts his adventures twice a week to his YouTube video blog, “The Geocaching Vlogger.” And families are well represented in geocaching.com, where you see lots of references to searching with kids.

“One of the reasons we do it is because it’s an easy way to get the boys outdoors and interested in a long bike ride or long hike,” said Darcy Schatz of Eagan, who frequently geocaches with her three sons. “Our kids will hike for miles if they know there is a geocache at the end.”

Her oldest, Alex, 13, even created a cache of his own a couple of years ago, hiding a tennis ball can in a tree in a park near his house.

It’s too early to say whether our family will get hooked on geocaching. The kids and I want to return to Fort Snelling State Park and find the Avian Adventure cache. In the meantime, I looked at geocaching.com and pulled up 30 caches within a mile of our house, including ones at tiny city parks I had never noticed.

Some require hunters to complete puzzles to decipher the coordinates, such as one that involves answering questions about Pokemon and another near the University of Minnesota veterinary school that involves naming cuts of beef on a chart.

On a recent weekday morning I asked my daughter if she wanted to look for a cache in a city park near her school. While the first children streamed toward the school building at one end of the park, we walked nonchalantly toward an empty playground at the other end. She held the phone and followed the compass arrow to a tree. We looked for a while, and she finally saw it, a black film canister. It was too small to hold swag, but she didn’t care. She was thrilled with the find and eager to talk about it.

“At first, I thought it was a chunk of dirt,” she explained, after we replaced the cache when no one was looking and resumed our walk to school. “But then I saw it was glossy, and I knew I had found it!”

Tips: First-timers should look for a cache rated easy, on easy terrain, and with comments indicating that it has been found recently

Special events: The Minnesota Geocaching Association is holding a geocaching weekend at William O’Brien Park, Sept. 22 and 23. Drop by the picnic grounds to borrow a GPS unit and get tips on how to search for temporary caches. Geocaching classes are held at state parks, including one coming up at William O’Brien at 10:30 a.m. Oct. 13. Registration required. For information about both events, call 651-433-0500 or go to dnr.state.mn.us.

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